Conventionally, lumbar support assemblies are used for maintaining a seat cushion in a contoured position. Such lumbar support assemblies usually include either bellows, air bladders, or a pump to force air into the cushion pocket to reach the desired contour. Alternatively, a semi-rigid mechanical structure which can be moved in a plurality of predetermined positions to adjust the contour of the seat in the lumbar area is also known.
U.S. Pat. No. 5,076,643, issued Dec. 31, 1991 in the name of Colasanti et al, and assigned to the assignee of the subject invention, discloses a lumbar support assembly having a seat frame with a pneumatic bladder supported thereon, and a contoured plate disposed over the bladder having a free end slidably engaged within guides. As the bladder is inflated or deflated, the plate responds thereto providing lumbar support as required.
U.S. Pat. No. 5,137,329, issued Aug. 11, 1992 in the name of Neale discloses an adjustable lumbar support including a rigid back plate and front plate which provides support. The contour of the front plate is generally concave, and a fluid actuator is placed between the plates to provide additional or less support.
U.S. Pat. No. 5,190,348 to Colasanti also discloses an inflatable bladder acting with an arcuate plate.
U.S. Pat. No. 3,145,054 and U.S. Pat. No. 5,054,854 disclose the use of multiple air bladders to provide selective support.